Mineral Review

Which gemstone changes its color?

Gemstones that change colors are charming because they prevent the jewelry from becoming boring. A ring or earrings with such a mineral look different depending on the lighting, temperature, and mood. Because of this feature, chameleon gems are always popular and are valued more than classic single-color crystals.

Why do stones change color?

Pleochroism is a natural feature that is quite rare in mineralogy. This phenomenon is due to the “behavior” of impurities in natural stone; “additives” react to changes in light, temperature or humidity. But it is worth considering that many minerals change color when exposed to high temperatures (several hundred degrees) or under the influence of radioactive radiation. Such changes in shade are not considered a chameleon effect, but are called “ennobling”. This treatment is carried out to improve the color of the crystal. True, heating or radiation do not provide any guarantees. After refining, the stone can become either bright and beautiful, or, conversely, fade or become cloudy. Read also: Processing of precious stones (refinement): methods, table and process The photo below shows natural topaz in its natural form (left), as well as after refinement by radioactive radiation and roasting (right). Another color change that is not considered a chameleon is fading. Some minerals lose their color when exposed to direct sunlight for a long time. It is not recommended to wear jewelry with such stones in the summer, much less wear them when visiting the beach. This is how kunzites, some quartz, refined topazes, heliodors, etc. behave.

List

In fact, the list of gemstones that change color is not that long. At the same time, not all minerals of one type are 100% chameleons. Most often, this feature is inherent only in some pieces of jewelry quality. Opaque cloudy color crystals are changed extremely rarely.

From lighting

The most common stones are those that change color depending on the light. For some minerals, the shade depends on the time of day, while for others it depends on whether the crystal is in artificial or natural light.

Alexandrite

Alexandrite is perhaps the most famous chameleon stone. This is why the color changing effect is often called “Alexandrite”. In daylight, the mineral has green tints, and in the evening rays its edges become red-crimson. There is even a humorous saying that alexandrite becomes an emerald in the morning and a ruby ​​in the evening. But a similar effect is present only in natural minerals. It is worth noting that the price of natural gem-quality alexandrite is quite high. Small stones (weighing up to 5 carats) are estimated at $3000–5000 per 1 ct. The cost of large crystals of 5–10 ct can reach $15000 per 1 carat. Unique specimens weighing more than 10 ct are usually sold only at famous world auctions and they can be valued at either 30 or 000 USD. per carat

Amethyst

The color change in amethyst is slight. The difference becomes noticeable in artificial and natural light. The origin of the stone matters. Specimens obtained in the Urals, under artificial light, acquire a rich violet-red hue. In turn, gems from Brazilian deposits, on the contrary, become more faded and even grayish. When choosing a ring or earrings with amethyst, it is important to remember that this mineral is characterized by “fading”. That is, over time, a natural crystal may lighten and become less bright. The rate of color loss depends on the place where the gem was mined and the conditions of care. This way, when using jewelry in intense sunlight, the bleaching process will occur faster.

Garnet

The effect of color change is most noticeable in the blue variety of garnet. But such specimens are extremely rare; they can literally be counted on one hand. Blue garnets do not have a separate deposit; in unique cases, they are found in other mining areas (most often in Tanzania). These members of the extensive garnet family change color from grayish blue to rich green in daylight and deepen to red and purple in artificial light. Blue garnets are exclusive specimens that are scattered into private collections immediately after extraction. If a jewelry store offers a similar stone, you can be 99% sure that it is a fake. Pyrope is a red variety of garnet, which is also credited with the ability to change color, or rather saturation of hue. In some cases it becomes blood red, while in others it becomes duller and more faded. Read also: Garnet stone: properties, colors and meaning of a natural mineral (35 photos)

Sapphire

Sapphires that change color are extremely rare. Such stones are considered unique and are valued very highly. It is impossible to find such a specimen (large) on the shelves of jewelry stores. Chameleon sapphire has a rich blue color in daylight, but in artificial light the hue changes to purple, lilac, pinkish, greenish or yellowish.

Sultanite

Sultanite (also known as zultanite or Turkey stone) changes its color from olive green to orange or pink depending on the angle of view or the nature of the color source. In the sun, the stone is characterized by green shades, and under an incandescent lamp it acquires orange or pinkish tones. The same effect can be obtained if you twist the crystal at different angles: both green and orange highlights will appear in it.

Tourmaline

Not every tourmaline has the effect of pleochroism. Only specimens of a dark blue hue – indigolites – can be chameleons. It is enough to turn a semi-precious stone to notice that at some angles its color becomes deeper and more saturated. Read also: Rubellite stone (pink tourmaline): properties and shades with photos

Spinel

Natural spinel quite often has an alexandrite effect, but this only applies to the noble variety of the mineral. The most common change in shade is from blue to red or pink. This is achieved due to the presence of cobalt and chromium impurities in the mineral. Most often, chameleons are found among Ceylon spinels (10–15% of all production). If the stone has a silvery-grayish tint, as in the photo below, then this indicates that it belongs to the mines of Burma (Myanmar).

From temperature

Apart from refinement by heating, stones that change color depending on temperature practically do not exist in nature. Amethyst can be considered the only representative of this section. Amethyst is not only a stone of day and night, the purple mineral can change color depending on temperature. This effect is noticeable upon contact with a hot body or exposure to sunlight. The higher the temperature, the lighter the gem.

From the mood

Changing the color of a stone depending on your mood is a rather controversial issue. Some argue that the shades change significantly, others – that these are all fictions, like the magical properties of minerals or lithotherapy (the healing properties of the stone). In any case, there are a number of minerals that are considered to change color depending on the mood of their owner and his surroundings (emotions, events, etc.).

Agate

Agate is credited with the ability to change color depending on the mood and health of its owner. Similar statements appeared after the publication of Harry Benjamin and his legend about the occult ring of Helena Blavatsky. This lady was fond of mysticism and esotericism, and her jewelry was called a “magic ring.” The story is quite confusing, without citing any sources or reliable evidence. According to one version, an agate was inserted into the magic ring, which turned black on the day of Helena Blavatsky’s death, as if warning her of danger. According to other versions, it was hematite; there is also an opinion that the stone in the ring was a tiger’s eye, and the “magic” of the jewelry lay in the presence of a “secret,” that is, a hiding place. In any case, after this story, agate began to be credited with the effect of changing color, depending on the mood of the owner. But this statement is very doubtful, since chameleons are usually transparent or translucent stones, but agate is not.

Aquamarine

Since ancient times, transparent blue aquamarine has served as a “barometer” for sailors. It is believed that the stone can warn of storms. Moreover, this applies to both the weather forecast and mood. According to legend, if bad weather or a storm of emotions is coming, the stone becomes cloudy and acquires a greenish tint. The rest of the time the crystal remains transparent blue.

In ultraviolet (UV) rays

In this case, it is difficult to talk about changing the color. In ultraviolet light, stones most often do not change color, but begin to glow in neon shades, as shown in the photo below. This property of minerals is called fluorescence.

Amethyst

Classic purple amethyst acquires a faint green glow when exposed to UV rays.

Apatite

Inconspicuous colorless or yellow-green apatite glows brightly in ultraviolet light (photo below).

Diamond

A cut diamond also exhibits fluorescence. Since it is the impurities that “glow,” this effect is most pronounced in colored stones. Colorless diamonds also glow, but not as clearly. The purest specimens may not change color at all in ultraviolet light. But more often synthetic crystals do not react to UV rays.

Calcite

In natural light, calcite is usually pinkish, brownish, or beige. In ultraviolet light, transparent and translucent minerals change color to purple, lilac, pink, or red.

Quartz

The quartz family is very extensive. It contains many minerals of different types and shades. Not all stones belonging to this type glow. But by choosing the right wavelength, you can see a weak yellow or bluish glow.

Opal

In principle, noble opal can also be considered a stone that changes light depending on the lighting. After all, from different angles, impurities glare in different shades. But, in addition to this, the stone is characterized by fluorescence. In addition, some specimens glow not only in ultraviolet light, but also in daylight (photoluminescence).

Ruby

Natural rubies glow actively in ultraviolet light. The shade of the glow in this case is extremely important, because it helps to distinguish a natural stone from a fake.

Fluorite

The very name of the mineral fluorite hints at the presence of fluorescence, but in addition to it, the stone also has thermoluminescence, that is, it begins to glow when heated. The color of the glow is pronounced blue, purple or green.

Zircon

Depending on the original color of the zircon (top row in the photo below), it can glow blue, yellow, pink or red. In this case, the intensity of the glow depends on the wavelength (bottom two rows).

Amber

Amber is another stone that glows under ultraviolet light. Moreover, some specimens glow not only in UV rays, but also in the dark.

For other reasons

There are a number of other unusual reasons why stones can change color.

Moonstone

Moonstone got its name for a reason. Its color changes depending on the phase of the moon. During the new moon, the mineral becomes almost opaque, white and loses its shine. In turn, as the full moon approaches, the stone becomes almost transparent and acquires a bluish-lilac tint.

Opal

If you wet a noble opal, it will lose its fascinating play of light and turn into a low-value cobblestone, but this only applies to hydrophane opals. There is just a nuance: only a specialist can determine whether a stone is a hydrophane. For everyone else, it is not recommended to wet opals.

Conclusion

Stones can change color for various reasons, this is beautiful and unusual. But the color-changing mineral is not always a chameleon. How useful is the publication? Click on a star to rate! Average rating 5 / 5. Number of ratings: 1 No ratings yet. Be the first to rate. Celebrated London jeweler Edwin Streeter described the color-changing gemstone alexandrite as “emerald by day and amethyst by night.” Seeing a color changing gemstone in action is an amazing sight. Outside, in normal daylight, gemstones may appear green, blue, yellow, or any other color, and then once they are placed indoors, they will change color to red, orange, purple, or any of a variety of colors. It’s almost magical. If you watch the effect on video, it looks like some kind of trick with the camera or lighting. There are several gemstones with this color-changing ability, including color-changing sapphire, color-changing garnet, color-changing diaspore, and, most famously, alexandrite. All with subtle differences in color and their ability to change not only in different light sources, but also at different times of the day!

But how does this happen?

A quick science lesson. Imagine that you are looking at a red apple. When we look at an object we see reflected light (this is a very common science lesson) so all the colors of light hit the apple and all the colors are absorbed by the apple except red which is reflected back so the apple looks red. Different lighting settings can affect what colors we see. For example, a blue sapphire in candlelight will be different from a sapphire in sunlight. Candlelight is rich in red wavelengths but poor in blue wavelengths, so when you look at a sapphire under candlelight, it appears almost black because there is no blue wavelength there to reflect. Experienced gem dealers know exactly what light is best for their gemstones, even taking into account the time of day and direction of the sun. The same effects are used to make our faces look good in restaurants and our vegetables look delicious in supermarkets. Daylight contains more blue and green light and less red light, incandescent light has more red light and less blue and green light. In addition, the temperature of the air around us also affects the light: cool mornings tend to look bluer than warm afternoons, causing gemstones to appear redder. These lighting conditions affect everything we see, from fruits to leaves to gems, and the chemical composition of each object also affects its color. Rubies are the red form of the mineral corundum, corundum is aluminum and oxygen, and is colorless unless minute impurities are added. In the case of rubies, traces of chromium replace aluminum. Chromium atoms absorb all light except red light, which is what gives rubies their deep red color. Other minor chemical changes cause discoloration of gemstones, usually chromium or vanadium. It is unknown exactly how this phenomenon occurs at this atomic level, but crystal angles, rutile inclusions, and infinitesimal variations in the chemical structure will play a role. Enough science, what about gemstones? The most famous color-changing gemstone is alexandrite, discovered in the Urals in Russia and named after the future Tsar Alexander II. His discovery in Russia, as well as the red and green colors of the Russian army uniform, strengthened his connection with that country. Alexandrite is a type of chrysoberyl that is one of the most valuable gemstones in the world. Finding alexandrite from Russia is now very difficult, and almost impossible to find anywhere else. In 1987, alexandrite was discovered in a valley in Brazil, and within a few weeks, 3000 miners descended a ridge just 200 meters long and began digging. On average, a person a week was shot in a dispute over mining rights, and in the four months before the mine was depleted, it was estimated that two hundred and fifty thousand carats (50 kg) had been mined. Pomegranates have perhaps the greatest variety of colors of any gemstone in the world, and its color-changing variety is one of the most attractive. This exquisite example ranges from pale yellow to deep orange and rich honey to golden brown. To our knowledge, it has never been processed and is produced as large clear gemstones in a wide variety of cuts and cuts. Diaspore changing color is another beautiful gemstone that turns kiwi green in natural light, but changes color to champagne yellow when lit by incandescent lights. The third color can be seen in candlelight when the gemstone takes on a pinkish tint. Its name comes from the Greek “to scatter” due to its sparkling appearance. High quality color changing Diaspore can be found locally in Turkey and is sold under the name Zultanite or Csarite. One of the most valuable and popular color changing gemstones is Sapphire . These are generally very clear gemstones that are most often found in smaller sizes and cut for maximum color variation. Like most sapphires, color-changing gemstones are heat treated to enhance their appearance. Color changing fluorite is a fairly soft gemstone, so it should be used for pendants, necklaces or brooches when used as jewelry or simply kept as a charming free-standing gemstone. Its intense color change is a remarkable phenomenon to behold as it changes dramatically from blue to purple. This usually untreated gemstone comes in lovely large sizes and has creative cuts that really show off its beauty. Hyalite opal is a relatively new product in the world of gemstones. changing color and what an impressive debut. Hyalite opals are usually clear, colorless or slightly yellow in normal light, but under UV light or sunlight they glow a dramatic dark green. In the case of Hyalite Opal, this color change is known as fluorescence. Fluorescent objects instantly light up when exposed to ultraviolet radiation – it is almost impossible to see this in action. Another color-changing gemstone we know of is Andesine, which comes from the Congo, China and Tibet, which supposedly changes color from dark green to bright purple, but it is very rare and may be of dubious origin, so we reserve a judgment until we see it. ourselves. That’s it, just six varieties of gemstones that are so rare that they are called “phenomenal gemstones.” Each gem is an unusual object of beauty even of the same color, and they make a magical leap with this unusual ability.

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